Method and apparatus for creating ocular surgical and relaxing incisions

ABSTRACT

A system and method of treating target tissue in a patient&#39;s eye, which includes generating a light beam, deflecting the light beam using a scanner to form first and second treatment patterns, delivering the first treatment pattern to the target tissue to form an incision that provides access to an eye chamber of the patient&#39;s eye, and delivering the second treatment pattern to the target tissue to form a relaxation incision along or near limbus tissue or along corneal tissue anterior to the limbus tissue of the patient&#39;s eye to reduce astigmatism thereof.

RELATED APPLICATIONS

This application is a continuation application under 35 USC § 120 ofU.S. patent application Ser. No. 13/569,103 filed Aug. 7, 2012, whichclaims priority to and is a divisional of U.S. patent application Ser.No. 12/048,186, filed Mar. 13, 2008, which claims the benefit of U.S.Provisional Application No. 60/906,944, filed Mar. 13, 2007, and whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to ophthalmic surgical procedures andsystems.

BACKGROUND OF THE INVENTION

Cataract extraction is one of the most commonly performed surgicalprocedures in the world with estimated 2.5 million cases performedannually in the United States and 9.1 million cases worldwide in 2000.This was expected to increase to approximately 13.3 million estimatedglobal cases in 2006. This market is composed of various segmentsincluding intraocular lenses for implantation, viscoelastic polymers tofacilitate surgical maneuvers, disposable instrumentation includingultrasonic phacoemulsification tips, tubing, and various knives andforceps. Modern cataract surgery is typically performed using atechnique termed phacoemulsification in which an ultrasonic tip with anassociated water stream for cooling purposes is used to sculpt therelatively hard nucleus of the lens after performance of an opening inthe anterior lens capsule termed anterior capsulotomy or more recentlycapsulorhexis. Following these steps as well as removal of residualsofter lens cortex by aspiration methods without fragmentation, asynthetic foldable intraocular lens (IOLs) is inserted into the eyethrough a small incision.

Many cataract patients are astigmatic. Astigmatism can occur when thecornea has a different curvature one direction than the other. IOLs arenot presently used to correct beyond 5D of astigmatism, even though manypatients have more severe aberrations. Correcting it further ofteninvolves making the corneal shape more spherical, or at least moreradially symmetrical. There have been numerous approaches, includingCorneaplasty, Astigmatic Keratotomy (AK), Corneal Relaxing Incisions(CRI), and Limbal Relaxing Incisions (LRI). All are done using manual,mechanical incisions. Presently, astigmatism cannot easily orpredictably be corrected fully using standard techniques and approaches.About one third of those who have surgery to correct the irregularityfind that their eyes regress to a considerable degree and only a smallimprovement is noted. Another third of the patients find that theastigmatism has been significantly reduced but not fully corrected. Theremaining third have the most encouraging results with most or all ofthe desired correction achieved.

What is needed are ophthalmic methods, techniques and apparatus toadvance the standard of care of corneal shaping that may be associatedwith invasive cataract and other ophthalmic pathologies.

SUMMARY OF THE INVENTION

Rapid and precise opening formation in the cornea and/or limbus arepossible using a scanning system that implements patterned lasercutting. The patterned laser cutting improves accuracy and precision,while decreasing procedure time.

A scanning system for treating target tissue in a patient's eye includesa light source for generating a light beam, a scanner for deflecting thelight beam to form first and second treatment patterns of the light beamunder the control of a controller, and a delivery system for deliveringthe first treatment pattern to the target tissue to form a cataractincision therein that provides access to an eye chamber of the patient'seye. The delivery system is also for delivering the second treatmentpattern to the target tissue to form a relaxation incision along or nearlimbus tissue or along corneal tissue anterior to the limbus tissue ofthe patient's eye to reduce astigmatism thereof.

A method of treating target tissue in a patient's eye includesgenerating a light beam, deflecting the light beam using a scanner toform first and second treatment patterns, delivering the first treatmentpattern to the target tissue to form an incision that provides access toan eye chamber of the patient's eye, and delivering the second treatmentpattern to the target tissue to form a relaxation incision along or nearlimbus tissue or along corneal tissue anterior to the limbus tissue ofthe patient's eye to reduce astigmatism thereof.

Other objects and features of the present invention will become apparentby a review of the specification, claims and appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the optical beam scanning system.

FIG. 2 is an optical diagram showing an alternative beam combiningscheme.

FIG. 3 is a schematic diagram of the optical beam scanning system withan alternative OCT configuration.

FIG. 4 is a schematic diagram of the optical beam scanning system withanother alternative OCT combining scheme.

FIG. 5A is a top view of a patient's eye showing a cataract incision.

FIG. 5B is a side cross sectional view of a patient's eye showing thecataract incision.

FIG. 6 is a schematic diagram of the optical beam scanning system with aprofilometer subsystem.

FIG. 7 is a top view of a patient's eye showing corneal relaxingincisions.

FIG. 8 is a side cross sectional view of a patient's eye showing anincision with a specialized geometry.

FIG. 9 is a side cross sectional view of a contact lens in proximity toa patient's eye.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The techniques and systems disclosed herein provide many advantages overthe current standard of care. Specifically, rapid and precise openingsin the cornea and/or limbus are formed using 3-dimensional patternedlaser cutting. The accuracy and precision of the incisions are improvedover traditional methods, while the duration of the procedure and therisk associated with creating incisions are both reduced. The presentinvention can utilize anatomical and optical characterization andfeedback to perform astigmatic keratotomy such as limbal and cornealrelaxing incisions in conjunction with the creation of surgical incisionthat provides the surgeon access to the anterior chamber of an eye. Thesurgical incision may be made completely, or partially, depending uponthe clinical situation. A wavefront sensor, interferometer, surfaceprofiler, or other such device may be used to yield prescriptions forcorrecting the astigmatism or other visual aberrations. Likewise, thesesame devices may be used to verify the surgical correction of thepatterned scanning system, even adjusting it during the treatmentprocedure to produce the desired outcome. Furthermore, the presentinvention may be used in multiple sessions to coordinate the healing ofthe astigmatic correction, and drive the corrective treatment over thecourse of the wound healing process. The present invention also providesfor the image guided alignment of the incision.

There are surgical approaches provided by the present invention thatenable the formation of very small and geometrically precise opening(s)and incision(s) in precise locations in and around the cornea andlimbus. The incisions enable greater precision or modifications toconventional ophthalmic procedures as well as enable new procedures. Theincision is not limited only to circular shapes but may be any shapethat is conducive to healing or follow on procedures. These incisionsmight be placed such that they are able to seal spontaneously; or withautologous or synthetic tissue glue, photochemical bonding agent, orother such method. Furthermore, the present invention provides for theautomated generation of incision patterns for optimal effect.

Another procedure enabled by the techniques described herein providesfor the controlled formation of an incision or pattern of incisions.Conventional techniques are confined to areas accessible from outsidethe eye using mechanical cutting instruments and thus can only createincisions from anterior to posterior segments of tissue. In contrast,the controllable, patterned laser techniques described herein may beused to create an incision in virtually any position and in virtuallyany shape. Matching incisions may be made in both the anterior andposterior sections. The present invention is uniquely suited to performsuch matching incisions.

Furthermore, these incisions may be tailored to complement an asymmetricIOL that is being inserted as part of the procedure or has beenpreviously inserted. The present invention enables the measurement ofthe IOL placement and subsequent automated calculation and generation ofthese complimentary corneal or limbus incisions. The controllable,patterned laser techniques described herein have available and/orutilize precise lens measurement and other dimensional information thatallows the incision or opening formation while minimizing impact onsurrounding tissue.

The present invention can be implemented by a system that projects orscans an optical beam into a patient's eye 68, such as system 2 shown inFIG. 1 which includes an ultrafast (UF) light source 4 (e.g. afemtosecond laser). Using this system, a beam may be scanned in apatient's eye in three dimensions: X, Y, Z. In this embodiment, the UFwavelength can vary between 1010 nm to 1100 nm and the pulse width canvary from 100 fs to 10000 fs. The pulse repetition frequency can alsovary from 10 kHz to 250 kHz. Safety limits with regard to unintendeddamage to non-targeted tissue bound the upper limit with regard torepetition rate and pulse energy; while threshold energy, time tocomplete the procedure and stability bound the lower limit for pulseenergy and repetition rate. The peak power of the focused spot in theeye 68 and specifically within the crystalline lens 69 and anteriorcapsule of the eye is sufficient to produce optical breakdown andinitiate a plasma-mediated ablation process. Near-infrared wavelengthsare preferred because linear optical absorption and scattering inbiological tissue is reduced across that spectral range. As an example,laser 4 may be a repetitively pulsed 1035 nm device that produces 500 fspulses at a repetition rate of 100 kHz and an individual pulse energy inthe ten microjoule range.

The laser 4 is controlled by control electronics 300, via an input andoutput device 302, to create optical beam 6. Control electronics 300 maybe a computer, microcontroller, etc. In this example, the entire systemis controlled by the controller 300, and data moved through input/outputdevice IO 302. A graphical user interface GUI 304 may be used to setsystem operating parameters, process user input (UI) 306 on the GUI 304,and display gathered information such as images of ocular structures.

The generated UF light beam 6 proceeds towards the patient eye 68passing through half-wave plate, 8, and linear polarizer, 10. Thepolarization state of the beam can be adjusted so that the desiredamount of light passes through half-wave plate 8 and linear polarizer10, which together act as a variable attenuator for the UF beam 6.Additionally, the orientation of linear polarizer 10 determines theincident polarization state incident upon beamcombiner 34, therebyoptimizing beamcombiner throughput.

The UF beam proceeds through a shutter 12, aperture 14, and a pickoffdevice 16. The system controlled shutter 12 ensures on/off control ofthe laser for procedural and safety reasons. The aperture sets an outeruseful diameter for the laser beam and the pickoff monitors the outputof the useful beam. The pickoff device 16 includes of a partiallyreflecting mirror 20 and a detector 18. Pulse energy, average power, ora combination may be measured using detector 18. The information can beused for feedback to the half-wave plate 8 for attenuation and to verifywhether the shutter 12 is open or closed. In addition, the shutter 12may have position sensors to provide a redundant state detection.

The beam passes through a beam conditioning stage 22, in which beamparameters such as beam diameter, divergence, circularity, andastigmatism can be modified. In this illustrative example, the beamconditioning stage 22 includes a 2 element beam expanding telescopecomprised of spherical optics 24 and 26 in order to achieve the intendedbeam size and collimation. Although not illustrated here, an anamorphicor other optical system can be used to achieve the desired beamparameters. The factors used to determine these beam parameters includethe output beam parameters of the laser, the overall magnification ofthe system, and the desired numerical aperture (NA) at the treatmentlocation. In addition, the optical system 22 can be used to imageaperture 14 to a desired location (e.g. the center location between the2-axis scanning device 50 described below). In this way, the amount oflight that makes it through the aperture 14 is assured to make itthrough the scanning system. Pickoff device 16 is then a reliablemeasure of the usable light.

After exiting conditioning stage 22, beam 6 reflects off of fold mirrors28, 30, & 32. These mirrors can be adjustable for alignment purposes.The beam 6 is then incident upon beam combiner 34. Beamcombiner 34reflects the UF beam 6 (and transmits both the OCT 114 and aim 202 beamsdescribed below). For efficient beamcombiner operation, the angle ofincidence is preferably kept below 45 degrees and the polarization wherepossible of the beams is fixed. For the UF beam 6, the orientation oflinear polarizer 10 provides fixed polarization.

Following the beam combiner 34, the beam 6 continues onto the z-adjustor Z scan device 40. In this illustrative example the z-adjust includesa Galilean telescope with two lens groups 42 and 44 (each lens groupincludes one or more lenses). Lens group 42 moves along the z-axis aboutthe collimation position of the telescope. In this way, the focusposition of the spot in the patient's eye 68 moves along the z-axis asindicated. In general there is a fixed linear relationship between themotion of lens 42 and the motion of the focus. In this case, thez-adjust telescope has an approximate 2× beam expansion ratio and a 1:1relationship of the movement of lens 42 to the movement of the focus.Alternatively, lens group 44 could be moved along the z-axis to actuatethe z-adjust, and scan. The z-adjust is the z-scan device for treatmentin the eye 68. It can be controlled automatically and dynamically by thesystem and selected to be independent or to interplay with the X-Y scandevice described next. Mirrors 36 and 38 can be used for aligning theoptical axis with the axis of z-adjust device 40.

After passing through the z-adjust device 40, the beam 6 is directed tothe x-y scan device by mirrors 46 & 48. Mirrors 46 & 48 can beadjustable for alignment purposes. X-Y scanning is achieved by thescanning device 50 preferably using two mirrors 52 & 54 under thecontrol of control electronics 300, which rotate in orthogonaldirections using motors, galvanometers, or any other well known opticmoving device. Mirrors 52 & 54 are located near the telecentric positionof the objective lens 58 and contact lens 66 combination describedbelow. Tilting these mirrors 52/54 causes them to deflect beam 6,causing lateral displacements in the plane of UF focus located in thepatient's eye 68. Objective lens 58 may be a complex multi-element lenselement, as shown, and represented by lenses 60, 62, and 64. Thecomplexity of the lens 58 will be dictated by the scan field size, thefocused spot size, the available working distance on both the proximaland distal sides of objective 58, as well as the amount of aberrationcontrol. An f-theta lens 58 of focal length 60 mm generating a spot sizeof 10 μm, over a field of 10 mm, with an input beam size of 15 mmdiameter is an example. Alternatively, X-Y scanning by scanner 50 may beachieved by using one or more moveable optical elements (e.g. lenses,gratings) which also may be controlled by control electronics 300, viainput and output device 302.

The aiming and treatment scan patterns can be automatically generated bythe scanner 50 under the control of controller 300. Such patterns may becomprised of a single spot of light, multiple spots of light, acontinuous pattern of light, multiple continuous patterns of light,and/or any combination of these. In addition, the aiming pattern (usingaim beam 202 described below) need not be identical to the treatmentpattern (using light beam 6), but preferably at least defines itsboundaries in order to assure that the treatment light is delivered onlywithin the desired target area for patient safety. This may be done, forexample, by having the aiming pattern provide an outline of the intendedtreatment pattern. This way the spatial extent of the treatment patternmay be made known to the user, if not the exact locations of theindividual spots themselves, and the scanning thus optimized for speed,efficiency and accuracy. The aiming pattern may also be made to beperceived as blinking in order to further enhance its visibility to theuser.

An optional contact lens 66, which can be any suitable ophthalmic lens,can be used to help further focus the optical beam 6 into the patient'seye 68 while helping to stabilize eye position. The positioning andcharacter of optical beam 6 and/or the scan pattern the beam 6 forms onthe eye 68 may be further controlled by use of an input device such as ajoystick, or any other appropriate user input device (e.g. GUI 304) toposition the patient and/or the optical system.

The UF laser 4 and controller 300 can be set to target the surfaces ofthe targeted structures in the eye 68 and ensure that the beam 6 will befocused where appropriate and not unintentionally damage non-targetedtissue. Imaging modalities and techniques described herein, such as forexample, Optical Coherence Tomography (OCT), Purkinje imaging,Scheimpflug imaging, or ultrasound may be used to determine the locationand measure the thickness of the lens and lens capsule to providegreater precision to the laser focusing methods, including 2D and 3Dpatterning. Laser focusing may also be accomplished using one or moremethods including direct observation of an aiming beam, OpticalCoherence Tomography (OCT), Purkinje imaging, Scheimpflug imaging,ultrasound, or other known ophthalmic or medical imaging modalitiesand/or combinations thereof. In the embodiment of FIG. 1, an OCT device100 is described, although other modalities are within the scope of thepresent invention. An OCT scan of the eye will provide information aboutthe axial location of the anterior and posterior lens capsule, theboundaries of the cataract nucleus, as well as the depth of the anteriorchamber. This information is then be loaded into the control electronics300, and used to program and control the subsequent laser-assistedsurgical procedure. The information may also be used to determine a widevariety of parameters related to the procedure such as, for example, theupper and lower axial limits of the focal planes used for cutting thelens capsule and segmentation of the lens cortex and nucleus, and thethickness of the lens capsule among others.

The OCT device 100 in FIG. 1 includes a broadband or a swept lightsource 102 that is split by a fiber coupler 104 into a reference arm 106and a sample arm 110. The reference arm 106 includes a module 108containing a reference reflection along with suitable dispersion andpath length compensation. The sample arm 110 of the OCT device 100 hasan output connector 112 that serves as an interface to the rest of theUF laser system. The return signals from both the reference and samplearms 106, 110 are then directed by coupler 104 to a detection device128, which employs either time domain, frequency or single pointdetection techniques. In FIG. 1, a frequency domain technique is usedwith an OCT wavelength of 920 nm and bandwidth of 100 nm.

Exiting connector 112, the OCT beam 114 is collimated using lens 116.The size of the collimated beam 114 is determined by the focal length oflens 116. The size of the beam 114 is dictated by the desired NA at thefocus in the eye and the magnification of the beam train leading to theeye 68. Generally, OCT beam 114 does not require as high an NA as the UFbeam 6 in the focal plane and therefore the OCT beam 114 is smaller indiameter than the UF beam 6 at the beamcombiner 34 location. Followingcollimating lens 116 is aperture 118 which further modifies theresultant NA of the OCT beam 114 at the eye. The diameter of aperture118 is chosen to optimize OCT light incident on the target tissue andthe strength of the return signal. Polarization control element 120,which may be active or dynamic, is used to compensate for polarizationstate changes which may be induced by individual differences in cornealbirefringence, for example. Mirrors 122 & 124 are then used to directthe OCT beam 114 towards beamcombiners 126 & 34. Mirrors 122 & 124 maybe adjustable for alignment purposes and in particular for overlaying ofOCT beam 114 to UF beam 6 subsequent to beamcombiner 34. Similarly,beamcombiner 126 is used to combine the OCT beam 114 with the aim beam202 described below.

Once combined with the UF beam 6 subsequent to beamcombiner 34, OCT beam114 follows the same path as UF beam 6 through the rest of the system.In this way, OCT beam 114 is indicative of the location of UF beam 6.OCT beam 114 passes through the z-scan 40 and x-y scan 50 devices thenthe objective lens 58, contact lens 66 and on into the eye 68.Reflections and scatter off of structures within the eye provide returnbeams that retrace back through the optical system, into connector 112,through coupler 104, and to OCT detector 128. These return backreflections provide the OCT signals that are in turn interpreted by thesystem as to the location in X, Y Z of UF beam 6 focal location.

OCT device 100 works on the principle of measuring differences inoptical path length between its reference and sample arms. Therefore,passing the OCT through z-adjust 40 does not extend the z-range of OCTsystem 100 because the optical path length does not change as a functionof movement of 42. OCT system 100 has an inherent z-range that isrelated to the detection scheme, and in the case of frequency domaindetection it is specifically related to the spectrometer and thelocation of the reference arm 106. In the case of OCT system 100 used inFIG. 1, the z-range is approximately 1-2 mm in an aqueous environment.Extending this range to at least 4 mm involves the adjustment of thepath length of the reference arm within OCT system 100. Passing the OCTbeam 114 in the sample arm through the z-scan of z-adjust 40 allows foroptimization of the OCT signal strength. This is accomplished byfocusing the OCT beam 114 onto the targeted structure whileaccommodating the extended optical path length by commensuratelyincreasing the path within the reference arm 106 of OCT system 100.

Because of the fundamental differences in the OCT measurement withrespect to the UF focus device due to influences such as immersionindex, refraction, and aberration, both chromatic and monochromatic,care must be taken in analyzing the OCT signal with respect to the UFbeam focal location. A calibration or registration procedure as afunction of X, Y Z should be conducted in order to match the OCT signalinformation to the UF focus location and also to the relate to absolutedimensional quantities.

Observation of an aim beam may also be used to assist the user todirecting the UF laser focus. Additionally, an aim beam visible to theunaided eye in lieu of the infrared OCT and UF beams can be helpful withalignment provided the aim beam accurately represents the infrared beamparameters. An aim subsystem 200 is employed in the configuration shownin FIG. 1. The aim beam 202 is generated by a an aim beam light source201, such as a helium-neon laser operating at a wavelength of 633 nm.Alternatively a laser diode in the 630-650 nm range could be used. Theadvantage of using the helium neon 633 nm beam is its long coherencelength, which would enable the use of the aim path as a laser unequalpath interferometer (LUPI) to measure the optical quality of the beamtrain, for example.

Once the aim beam light source generates aim beam 202, the aim beam 202is collimated using lens 204. The size of the collimated beam isdetermined by the focal length of lens 204. The size of the aim beam 202is dictated by the desired NA at the focus in the eye and themagnification of the beam train leading to the eye 68. Generally, aimbeam 202 should have close to the same NA as UF beam 6 in the focalplane and therefore aim beam 202 is of similar diameter to the UF beamat the beamcombiner 34 location. Because the aim beam is meant tostand-in for the UF beam 6 during system alignment to the target tissueof the eye, much of the aim path mimics the UF path as describedpreviously. The aim beam 202 proceeds through a half-wave plate 206 andlinear polarizer 208. The polarization state of the aim beam 202 can beadjusted so that the desired amount of light passes through polarizer208. Elements 206 & 208 therefore act as a variable attenuator for theaim beam 202. Additionally, the orientation of polarizer 208 determinesthe incident polarization state incident upon beamcombiners 126 and 34,thereby fixing the polarization state and allowing for optimization ofthe beamcombiners' throughput. Of course, if a semiconductor laser isused as aim beam light source 200, the drive current can be varied toadjust the optical power.

The aim beam 202 proceeds through a shutter 210 and aperture 212. Thesystem controlled shutter 210 provides on/off control of the aim beam202. The aperture 212 sets an outer useful diameter for the aim beam 202and can be adjusted appropriately. A calibration procedure measuring theoutput of the aim beam 202 at the eye can be used to set the attenuationof aim beam 202 via control of polarizer 206.

The aim beam 202 next passes through a beam conditioning device 214.Beam parameters such as beam diameter, divergence, circularity, andastigmatism can be modified using one or more well known beamingconditioning optical elements. In the case of an aim beam 202 emergingfrom an optical fiber, the beam conditioning device 214 can simplyinclude a beam expanding telescope with two optical elements 216 and 218in order to achieve the intended beam size and collimation. The finalfactors used to determine the aim beam parameters such as degree ofcollimation are dictated by what is necessary to match the UF beam 6 andaim beam 202 at the location of the eye 68. Chromatic differences can betaken into account by appropriate adjustments of beam conditioningdevice 214. In addition, the optical system 214 is used to imageaperture 212 to a desired location such as a conjugate location ofaperture 14.

The aim beam 202 next reflects off of fold mirrors 222 & 220, which arepreferably adjustable for alignment registration to UF beam 6 subsequentto beam combiner 34. The aim beam 202 is then incident upon beamcombiner 126 where the aim beam 202 is combined with OCT beam 114.Beamcombiner 126 reflects the aim beam 202 and transmits the OCT beam114, which allows for efficient operation of the beamcombining functionsat both wavelength ranges. Alternatively, the transmit and reflectfunctions of beamcombiner 126 can be reversed and the configurationinverted. Subsequent to beamcombiner 126, aim beam 202 along with OCTbeam 114 is combined with UF beam 6 by beamcombiner 34.

A device for imaging the target tissue on or within the eye 68 is shownschematically in FIG. 1 as imaging system 71. Imaging system includes acamera 74 and an illumination light source 86 for creating an image ofthe target tissue. The imaging system 71 gathers images which may beused by the system controller 300 for providing pattern centering aboutor within a predefined structure. The illumination light source 86 forthe viewing is generally broadband and incoherent. For example, lightsource 86 can include multiple LEDs as shown. The wavelength of theviewing light source 86 is preferably in the range of 700 nm to 750 nm,but can be anything which is accommodated by the beamcombiner 56, whichcombines the viewing light with the beam path for UF beam 6 and aim beam202 (beamcombiner 56 reflects the viewing wavelengths while transmittingthe OCT and UF wavelengths). The beamcombiner 56 may partially transmitthe aim wavelength so that the aim beam 202 can be visible to theviewing camera 74. Optional polarization element 84 in front of lightsource 86 can be a linear polarizer, a quarter wave plate, a half-waveplate or any combination, and is used to optimize signal. A false colorimage as generated by the near infrared wavelength is acceptable.

The illumination light from light source 86 is directed down towards theeye using the same objective lens 58 and contact lens 66 as the UF andaim beam 6, 202. The light reflected and scattered off of variousstructures in the eye 68 are collected by the same lenses 58 & 66 anddirected back towards beamcombiner 56. There, the return light isdirected back into the viewing path via beam combiner and mirror 82, andon to camera 74. Camera 74 can be, for example but not limited to, anysilicon based detector array of the appropriately sized format. Videolens 76 forms an image onto the camera's detector array while opticalelements 80 & 78 provide polarization control and wavelength filteringrespectively. Aperture or iris 81 provides control of imaging NA andtherefore depth of focus and depth of field. A small aperture providesthe advantage of large depth of field which aids in the patient dockingprocedure. Alternatively, the illumination and camera paths can beswitched. Furthermore, aim light source 200 can be made to emit in theinfrared which would not directly visible, but could be captured anddisplayed using imaging system 71.

Coarse adjust registration is usually needed so that when the contactlens 66 comes into contact with the cornea, the targeted structures arein the capture range of the X, Y scan of the system. Therefore a dockingprocedure is preferred, which preferably takes in account patient motionas the system approaches the contact condition (i.e. contact between thepatient's eye 68 and the contact lens 66. The viewing system 71 isconfigured so that the depth of focus is large enough such that thepatient's eye 68 and other salient features may be seen before thecontact lens 66 makes contact with eye 68.

Preferably, a motion control system 70 is integrated into the overallcontrol system 2, and may move the patient, the system 2 or elementsthereof, or both, to achieve accurate and reliable contact betweencontact lens 66 and eye 68. Furthermore, a vacuum suction subsystem andflange may be incorporated into system 2, and used to stabilize eye 68.The alignment of eye 68 to system 2 via contact lens 66 may beaccomplished while monitoring the output of imaging system 71, andperformed manually or automatically by analyzing the images produced byimaging system 71 electronically by means of control electronics 300 viaIO 302. Force and/or pressure sensor feedback may also be used todiscern contact, as well as to initiate the vacuum subsystem.

An alternative beamcombining configuration is shown in the alternateembodiment of FIG. 2. For example, the passive beamcombiner 34 in FIG. 1can be replaced with an active combiner 140 in FIG. 2. The activebeamcombiner 34 can be a moving or dynamically controlled element suchas a galvanometric scanning mirror, as shown. Active combiner 140changes it angular orientation in order to direct either the UF beam 6or the combined aim and OCT beams 202,114 towards the scanner 50 andeventually eye 68 one at a time. The advantage of the active combiningtechnique is that it avoids the difficulty of combining beams withsimilar wavelength ranges or polarization states using a passive beamcombiner. This ability is traded off against the ability to havesimultaneous beams in time and potentially less accuracy and precisiondue to positional tolerances of active beam combiner 140.

Another alternate embodiment is shown in FIG. 3 which is similar to thatof FIG. 1 but utilizes an alternate approach to OCT 100. In FIG. 3, OCT101 is the same as OCT 100 in FIG. 1, except that the reference arm 106has been replaced by reference arm 132. This free-space OCT referencearm 132 is realized by including beamsplitter 130 after lens 116. Thereference beam 132 then proceeds through polarization controllingelement 134 and then onto the reference return module 136. The referencereturn module 136 contains the appropriate dispersion and path lengthadjusting and compensating elements and generates an appropriatereference signal for interference with the sample signal. The sample armof OCT 101 now originates subsequent to beamsplitter 130. The potentialadvantages of this free space configuration include separatepolarization control and maintenance of the reference and sample arms.The fiber based beam splitter 104 of OCT 101 can also be replaced by afiber based circulator. Alternately, both OCT detector 128 andbeamsplitter 130 might be moved together as opposed to reference arm136.

FIG. 4 shows another alternative embodiment for combining OCT beam 114and UF beam 6. In FIG. 4, OCT 156 (which can include either of theconfigurations of OCT 100 or 101) is configured such that its OCT beam154 is coupled to UF beam 6 after the z-scan 40 using beamcombiner 152.In this way, OCT beam 154 avoids using the z-adjust. This allows the OCT156 to possibly be folded into the beam more easily and shortening thepath length for more stable operation. This OCT configuration is at theexpense of an optimized signal return strength as discussed with respectto FIG. 1. There are many possibilities for the configuration of the OCTinterferometer, including time and frequency domain approaches, singleand dual beam methods, swept source, etc, as described in U.S. Pat. Nos.5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613 (which areincorporated herein by reference.)

The present invention provides for creating the incision to allow accessfor the lens removal instrumentation, typically referred to as the“cataract incision.” This is shown as cataract incision 402 on thepatient's eye 68 illustrated in FIGS. 5A & 5B. In these figures cataractincision 402 is made to eye 68 to provide access to crystalline lens 412through cornea 406 while pupil 404 is dilated. The incision 402 is shownin cornea 406, but could be alternately placed in limbus 408 or sclera410. The incision may be made with adjustable arcuate dimensions (bothradius and extent), radial orientation and depth. A complete cut may notbe desirable in all situations, such as in an unsterile field whereopening the eye to the environment poses further risks ofendophthalmitis, for example. In this case, the present invention mayprovide a cataract incision that only partially penetrates cornea 406,limbus 408 and/or sclera 410. The resident imaging apparati in system 2may also provide input for planning the incision. For example, imagingsystem 71 and/or OCT 100 could identify the limbal boundary, and guidethe incision to follow it along at a predetermined depth. Furthermore,surgeons often have difficulty in starting the incision at the correctlocation relative to limbus 410 when employing cold steel techniques, aswell as keeping the knife straight to avoid incisions that ultimatelypenetrate both cornea 406 and sclera 410. Such angled incisions provemore likely to have torn edges and significantly higher risks ofendophthalmitis.

The present invention may make use of the integrated OCT system 100 todiscern limbus 408 and sclera 410 relative to cornea 406 by virtue ofthe large optical scattering differences between them. These can bedirectly imaged using OCT device 100, and the location of the transition(limbus 408) from clear (cornea 406) to scattering (sclera 410) can bedetermined and used by CPU 300 of system 2 to guide the placement of thelaser-created incisions. The scanner position values corresponding tothis transition define the location of limbus 408. Thus, once registeredto each other, OCT 100 can guide the position of beam 6 relative tolimbus 408. This same imaging approach may be used to discern thethickness of the tissue, as well. Thus, the depth of the incisions andtheir disposition within the tissue may be precisely defined. With thatin mind, the choice of wavelength for OCT device 100 preferably accountsfor the requirement of scleral measurement. Wavelengths in the range of800-1400 nm are especially suited for this, as they are less scatteredin tissue (and penetrate to depths of ˜1 mm) while not suffering fromlinear optical absorption by water or other tissue constituents thatwould otherwise diminish their performance.

Standard cataract incisions typically require ˜30° of limbal angle asseen from directly above the eye. Such incisions have been shown toinduce from 0-1.0D of astigmatism, on average. Thus, achievingpostoperative emmetropia can be made more difficult. To addressastigmatism, the present invention may also produce AstigmaticKerototomy (AK) incisions. Such incisions are routinely used to correctastigmatism by relaxing an asymmetrically shaped cornea along its steepaxis. Similar to the cataract incision, such relaxing incisions (RIs)must be accurately placed along or nearby the limbus and are known asLimbal Relaxing Incisions (LRIs). Relaxing incisions, however, are onlypartially penetrating incisions. They should leave at least 200 μm oftissue thickness in order to maintain its ongoing structural integrity.Similarly, Corneal Relaxing Incisions (CRIs) are incisions that areplaced anterior to the limbus in the clear corneal tissue to serve thesame clinical purpose of astigmatic correction. In addition to thespecific clinical details, the circumferential orientation and angularextent are also influenced by the cataract incision. Thus, with thepresent invention, the RIs may be planned and executed in conjunctionwith the cataract incision to achieve a better visual correction thanotherwise possible. To optimize the entire treatment, the cataractincision should not be placed at or near the steep axis of the cornea.If it is, only one RI is traditionally recommended. There are a varietyof nomograms based upon empirical observations that are currently usedby clinicians to prescribe the placement and extent of RIs. Theseinclude, but are not limited to, the Donnenfeld, Gills, Nichamin, andKoch nomograms.

FIG. 6 illustrates system 2 as shown in FIG. 1, but with a sub-system tocharacterize the astigmatism of the patient's cornea. Specifically, aprofilometer 415 distal to X-Y scanner 50 is included to allow for acontinuous unobstructed view of the cornea of patient's eye 68.Profilometer 415 and its sensor 417 are added to system 2 viabeamcombiner 419 and are connected as shown in FIG. 6 to the systemcontroller 300 through input/output bus 302. As compared to theconfiguration described in FIG. 1, in this embodiment, contact lens 66or its disposition relative to cornea 406 of eye 68 may have to bemodified, or compensated for, to suit the profilometer's mode ofoperation. This is because profilometer 415 requires the cornea to be inits natural state, not forced into contact with a surface and possiblyconforming to its shape, to accurately measure cornea 406 and providedata to system 2 for calculation and registration via input/output bus302 and control electronics 300. Alternately, contact lens 66 may beremoved from contact with the eye, and the diagnostic and therapeuticportions of system 2 made to traverse gap 421 to eye 68 as shown in FIG.9. The change in relationship between eye 68 and system 2 made byremoving contact lens 66 must then be accounted for in ranging andregistration of beams 6, 114, and 202. The use of OCT 100 to discern thelocation and shape of cornea 406 is especially useful in this regard, asthe reflection from cornea 406 will provide a very strong signal makingregistration straight forward.

In this embodiment, profilometer 415 may be used to prescribe anastigmatic keratotomy to correct the shape of a patient's cornea todiminish its astigmatism. The profilometer 415 may be a placido system,triangulation system, laser displacement sensor, interferometer, orother such device, which measures the corneal topography also known asthe surface profile or the surface sag (i.e. sagitta) of the cornea as afunction of the transverse dimension to some defined axis. This axis istypically the visual axis of the eye but can also be the optical axis ofthe cornea. Alternately, profilometer 415 may be replaced by a wavefrontsensor to more fully optically characterize the patient's eye. Awavefront sensing system measures the aberration of the eye's opticalsystem. A common technique for accomplishing this task is aShack-Hartmann wavefront sensor, which measures the shape of thewavefronts of light (surfaces of constant phase) that exit the eye'spupil. If the eye were a perfect optical system, these wavefronts wouldbe perfectly flat. Since the eye is not perfect, the wavefronts are notflat and have irregular curved shapes. A Shack-Hartmann sensor dividesup the incoming beam and its overall wavefront into sub-beams, dividingup the wavefront into separate facets, each focused by a microlens ontoa subarray of detection pixels. Depending upon where the focal spot fromeach facet strikes its subarray of pixels, it is then possible todetermine the local wavefront inclination (or tilt). Subsequent analysisof all facets together leads to determination of the overall wavefrontform. These deviations from the perfectly overall flat wavefront areindicative of the localized corrections that can be made in the cornealsurface. The measurements of the wavefront sensor may be used bycontroller 300 to automatically prescribe an astigmatic keratotomy viapredictive algorithms resident in the system, as mentioned above.

FIG. 7 shows a possible configuration of such an astigmatic keratotomy.In this example, eye 68 is shown and a set of relaxing incisions RI 420are made at locations within the area of the cornea 406. Likewise, as isknown in the art, such relaxing incisions may be made in the limbus 408,or sclera 410. Astigmatism is present when the cornea is not spherical;that is, it is steeper in one meridian than other (orthogonal) meridian.Determining the nature of the corneal shape is important, whether theastigmatism is “with-the-rule,” “against-the-rule,” or oblique. In“with-the-rule” astigmatism, the vertical meridian is steeper than thehorizontal meridian; in “against-the-rule” astigmatism, the horizontalmeridian is steeper than the vertical meridian. Limbal relaxingincisions (LRIs) are a modification of astigmatic keratotomy (AK), aprocedure to treat astigmatism. LRIs are placed on the far peripheralaspect of the cornea (the limbus), resulting in a more rounded cornea.Astigmatism is reduced, and uncorrected vision is improved. LRIs cancorrect astigmatism up to 8 diopters (D); however, the use of LRIs ispresently routinely reserved for corrections of 0.5-4 D of astigmatism.Although LRIs are a weaker corrective procedure compared to cornealrelaxing incisions (CRIs), LRIs produce less postoperative glare andless patient discomfort. In addition, these incisions heal faster.Unlike CRIs, making the incision at the limbus preserves the perfectoptical qualities of the cornea. LRIs are also a more forgivingprocedure, and surgeons often get excellent results, even with earlycases.

The desired length, number, and depth of relaxing incisions 420 can bedetermined using nomograms. A starting point nomogram can titratesurgery by length and number of LRIs. However, the length and placementcan vary based on topography and other factors. The goal is to reducecylindrical optical power and to absolutely avoid overcorrectingwith-the-rule astigmatism, because against-the-rule astigmatism shouldbe minimized. Relaxing incisions formed in the sclera, limbus, or corneaare generally used for cases of with-the-rule astigmatism and lowagainst-the-rule astigmatism. When using the relaxing incision inconjunction with against-the-rule astigmatism, the LRI can be movedslightly into the cornea, or, alternatively, the LRI could be placedopposite another relaxing incision in the sclera, limbus or cornea. Forpatients who have with-the-rule astigmatism or oblique astigmatism, therelaxing incision is made temporally, and the LRIs are placed at thesteep axis. The placement of the LRI should be customized to thetopography of the cornea. In cases of asymmetric astigmatism, the LRI inthe steepest axis can be elongated slightly and then shortened the sameamount in the flatter of the 2 steep axes. Paired LRIs do not have to bemade in the same meridian. Patients with low (<1.5 D) against-the-ruleastigmatism receive only a single LRI in the steep meridian, placedopposite to the cataract incision. However, if astigmatism is greaterthan 1.5 D, a pair of LRIs should be used. In against-the-ruleastigmatism cases, one pair of LRIs may be incorporated into thecataract incision. The length of the LRI is not affected by the presenceof the cataract incision. This is difficult to perform precisely withpresent methods. In low with-the-rule astigmatism cases, a single 6-mmLRI (0.6 mm in depth) is made at 90°. The LRI can be independent of thecataract incision in with-the-rule astigmatism cases (if the cataractincision is temporal and the LRI is superior).

Furthermore, unlike traditional cold steel surgical approaches tocreating incisions that must start at the outside and cut inwards, usinga light source for making these incisions allows for RI 420 to be madefrom the inside out and thus better preserve the structural integrity ofthe tissue and limit the risk of tearing and infection. Moreover, thecataract incision 402 and the relaxation incision(s) 420 can be madeautomatically using the imaging and scanning features of system 2. Apair of treatment patterns can be generated that forms incisions 402 and420, thus providing more accurate control over the absolute and relativepositioning of these incisions. The pair of treatment patterns can beapplied sequentially, or simultaneously (i.e. the pair of treatmentpatterns can be combined into a single treatment pattern that forms bothtypes of incisions). For proper alignment of the treatment beam pattern,an aiming beam and/or pattern from system 2 can be first projected ontothe target tissue with visible light indicating where the treatmentpattern(s) will be projected. This allows the surgeon to adjust andconfirm the size, location and shape of the treatment pattern(s) beforetheir actual application. Thereafter, the two or three dimensionaltreatment pattern(s) can be rapidly applied to the target tissue usingthe scanning capabilities of system 2.

Specialized scan patterns for creating alternate geometries for cataractincisions 402 that are not achievable using conventional techniques arealso possible. An example is illustrated in FIG. 8. A cross-sectionalview of an alternate geometry for cataract incision 402 is shown to havea bevel feature 430. Bevel feature 430 may be useful for wound healing,sealing, or locking Such 3-dimensional cataract incisions 402 can beachieved accurately and quickly utilizing the 3-dimensional scanningability of system 2. Although a beveled incision is shown, many suchgeometries are enabled using the present invention, and within itsscope. As before, the incision 402 is shown in cornea 406, but could bealternately placed in limbus 408 or sclera 410.

For large fields as when incisions are made in the outer most regionssuch as the limbus or sclera, a specialized contact lens can be used.This contact lens could be in the form of a gonioscopic mirror or lens.The lens does not need to be diametrically symmetric. Just one portionof the lens can be extended to reach the outer regions of the eye suchas the limbus 408 and sclera 410. Any targeted location can be reachedby the proper rotation of the specialized lens.

It is to be understood that the present invention is not limited to theembodiment(s) described above and illustrated herein, but encompassesany and all variations falling within the scope of the appended claims.For example, references to the present invention herein are not intendedto limit the scope of any claim or claim term, but instead merely makereference to one or more features that may be covered by one or more ofthe claims. All the optical elements downstream of scanner 50 shown inFIGS. 1, 3 and 4 form a delivery system of optical elements fordelivering the beam 6, 114 and 202 to the target tissue. Conceivably,depending on the desired features of the system, some or even most ofthe depicted optical elements could be omitted in a delivery system thatstill reliably delivers the scanned beams to the target tissue.

What is claimed is:
 1. A scanning system for treating a target tissue ina patient's eye, comprising: a first light source for generating atreatment light beam; a second light source for generating an imaginglight beam; a scanner configured to deflect the treatment light beam toform a treatment pattern under the control of a controller, the scannerfurther being configured to deflect the imaging light beam; and adelivery system configured to deliver the treatment light beam to thetarget tissue to form the treatment pattern, the delivery system beingfurther configured to deliver the imaging light beam to the targettissue such that the imaging beam is indicative of a focal position ofthe treatment light beam, wherein the target tissue is selected from thegroup consisting of the lens, lens capsule, cornea, limbus and sclera ofthe patient's eye.
 2. The system of claim 1, further comprising: acommon optical path comprising one or more optical elements fordelivering both the treatment light beam and the imaging light beam toat least one of the scanner and the delivery system.
 3. The system ofclaim 2, wherein the one or more optical elements comprises a beamcombiner for combining the treatment light beam and the imaging lightbeam.
 4. The system of claim 1, further comprising: measuring backreflections or scatter of the imaging light beam from structures at ornear the target tissue of the patient's eye, and wherein the controlleridentifies a location of the treatment light beam based on the measuredscattering properties.
 5. The system of claim 1, wherein the treatmentlight beam and the imaging light beam are delivered simultaneously. 6.The system of claim 1, wherein the second light source is an OCT lightsource and the imaging light beam is an OCT light beam.
 7. The system ofclaim 6, wherein the OCT light source is configured to emit wavelengthsbetween 800 and 1400 nm.
 8. The system of claim 1, further comprising: aprofilometer for measuring a surface profile of a surface of the corneaof the patient's eye.
 9. The system of claim 1, further comprising: athird light source for generating an aiming light beam, wherein thescanner is configured to deflect the aiming light beam to form an aimingpattern that is delivered to the target tissue and visually indicates aposition of the treatment pattern on the patient's eye.
 10. The systemof claim 1, further comprising: a camera for capturing an image of thetarget tissue; a display device for displaying the captured image; and agraphic user interface for modifying a composition and location of thetreatment pattern on the patient's eye.
 11. A scanning system fortreating a target tissue in a patient's eye, comprising: a first lightsource for generating a treatment light beam; an Optical CoherenceTomography (OCT) system comprising an OCT light source configured togenerate an OCT light beam; a scanner configured to deflect thetreatment light beam to form a treatment pattern under the control of acontroller, the scanner further being configured to deflect the OCTlight beam; and a delivery system configured to deliver the treatmentlight beam to the target tissue to form the treatment pattern, thedelivery system being further configured to deliver the OCT light beamto the target tissue such that the OCT light beam is indicative of afocal position of the treatment light beam.
 12. The system of claim 11,further comprising: a common optical path comprising one or more opticalelements for delivering both the treatment light beam and the OCT lightbeam to at least one of the scanner and the delivery system.
 13. Thesystem of claim 12, wherein the one or more optical elements comprises abeam combiner for combining the treatment light beam and the OCT lightbeam.
 14. The system of claim 11, where the target tissue is selectedfrom the group consisting of the lens, lens capsule, cornea, limbus andsclera of the patient's eye.
 15. The system of claim 11, furthercomprising: an OCT detector for measuring back reflections or scatter ofthe OCT light beam from structures at or near the target tissue of thepatient's eye, and wherein the controller identifies a location of thetreatment light beam based on the measured scattering properties. 16.The system of claim 11, wherein the treatment light beam and the OCTlight beam are delivered simultaneously.
 17. The system of claim 11,wherein the OCT light source is configured to emit an OCT light beamhaving wavelengths between 800 and 1400 nm.
 18. The system of claim 11,further comprising: a profilometer for measuring a surface profile of asurface of the cornea of the patient's eye.
 19. The system of claim 11,further comprising: A second light source for generating an aiming lightbeam, wherein the scanner is configured to deflect the aiming light beamto form an aiming pattern that is delivered to the target tissue andvisually indicates a position of the treatment pattern on the patient'seye.
 20. The system of claim 11, further comprising: a camera forcapturing an image of the target tissue; a display device for displayingthe captured image; and a graphic user interface for modifying acomposition and location of the treatment pattern on the patient's eye.